Patent Document 1 discloses a technique intended to improve vibration absorbing characteristics. In this technique, a seat cushion is designed such that a first human body support portion, which comes below the ischial tuberosity of a human body, has a smaller dynamic spring constant than a second human body support portion, which comes below the thighs, thereby taking a vibration removal action by using the second human body support portion as a motion supporting point. In addition, Patent Document 2 discloses a similar technique.